Some orderly nonmonotonicities in the trial-by-trial acquisition of conditioned suppression: Inhibition with reinforcement?

Abstract

The trial-by-trial acquisition of conditioned suppression was examined under a wide range of conditions. Frequently, the acquisition functions were nonmonotonic. In conditions containing four or more trials in sessions of 2 h or less, suppression, once established, tended to be significantly stronger on the first trial of a session than on one or more subsequent trials. The data from six conditions are presented to exemplify those under which nonmonotonicities did and did not occur. It is suggested that the nonmonotonicities are similar to effects described by Pavlov (1960, Lecture 14), effects which he believed reflected the growth of inhibition despite continuous reinforcement. Interpretations of the results in terms of reactive inhibition, short-term habituation, conditioned inhibition, inhibition of delay, and disinhibition are discussed.